Switching from Cycles to Eevee : material turns black
The entire model, as imported, consists of 2 layers of faces. (Presumably the importer's interpretation of double-sided faces.) The 'outer' layer is backfacing. It can be hidden by switching on 'Backface Culling' in EEVEE.

It would be safe, (having made a copy) to select any face on the model, then CtrlL select linked, and X delete the lot, leaving behind the correctly oriented faces. If you somehow managed to select the wrong shell, ShiftN > Flip, turn the remainder inside-out.

Steps to finding the problem in this case:


Switch on 'Face orientation' and 'Face Normal' overlays
Note the normals show outward-facing, but the orientation doesn't.. Eh?
H hide a face .. there's another one underneath